The B75 uses the same range of cables fitted to certain standard Brompton models.
Brompton cables are supplied pre cut for speed and convenience. Hence the different codes for different handlebar types and bike ages.
This speeds up our production line assembly processes when building bikes but also makes it more convenient for bike shop mechanics by saving them a bit of time when installing the cable as part of a service.
Be certain that you are ordering the correct cables for your bike. Your bikes serial number can be used to identify the original specification of your bike, if you are uncertain.
By specifying the cable needed for that type of handlebar, the mechanic can be confident they can quickly install the cable to the correct length and routing when the bike is folded or being ridden.